Embryology of the Inner Ear - A series of organ culture experiments were performed using explanted mouse embryo inner ear anlage. One study defined the sites of origin of inner ear sensory structures from the mouse otocyst and was summarized in the fate map. A transfilter study of neural induction of the embryonic murine inner ear. In vitro studies of surgical and biochemical manipulations of epithelial/mesenchymal interactions showed that the integrity of the cephalic otic mesenchyme was an importnat factor in orderly morphogenesis of labyrinthine form. This study also showed that with increasing embryonic age the following factors were sequentially determined: 1. cytodifferentiation of sensory hair cells, 2. Histogenesis of sensory structures, 3. Morphogenesis of the labyrinth. In vitro studies using a mouse model for congenital malformation (kreisler) confirmed that the kreisler inner ear will express its phenotype in vitro with the same heterogeneity of expression that occurs in vivo. Transfilter interaction of normal and abnormal (kreisler) tissues suggest that the brain alone does not control the expression of the kreisler gene but that there must be an earlier effect on the developing otic anlage.